c-common.c (noplt): New attribute.
2015-06-04 Sriraman Tallam <tmsriram@google.com> * c-family/c-common.c (noplt): New attribute. (handle_noplt_attribute): New handler. * calls.c (prepare_call_address): Check for noplt attribute. * config/i386/i386.c (ix86_expand_call): Check for noplt attribute. (ix86_nopic_noplt_attribute_p): New function. (ix86_output_call_insn): Output indirect call for non-pic no plt calls. * doc/extend.texi (noplt): Document new attribute. * doc/invoke.texi: Document new attribute. * testsuite/gcc.target/i386/noplt-1.c: New test. * testsuite/gcc.target/i386/noplt-2.c: New test. * testsuite/gcc.target/i386/noplt-3.c: New test. * testsuite/gcc.target/i386/noplt-4.c: New test. This patch does two things: * Adds new generic function attribute "noplt" that is similar in functionality to -fno-plt except that it applies only to calls to functions that are marked with this attribute. * For x86_64, it makes -fno-plt(and the attribute) also work for non-PIC code by directly generating an indirect call via a GOT entry. From-SVN: r224138
This commit is contained in:
Sriraman Tallam
Sriraman Tallam
parent
172f0ce5ab
commit
4bb794e25d
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@ -1,3 +1,17 @@
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2015-06-04 Sriraman Tallam <tmsriram@google.com>
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* c-family/c-common.c (noplt): New attribute.
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(handle_noplt_attribute): New handler.
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* calls.c (prepare_call_address): Check for noplt
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attribute.
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* config/i386/i386.c (ix86_expand_call): Check
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for noplt attribute.
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(ix86_nopic_noplt_attribute_p): New function.
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(ix86_output_call_insn): Output indirect call for non-pic
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no plt calls.
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* doc/extend.texi (noplt): Document new attribute.
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* doc/invoke.texi: Document new attribute.
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2015-06-04 Andrew MacLeod <amacleod@redhat.com>
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* coretypes.h: Include machmode.h, signop.h, wide-int.h, double-int.h,
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@ -356,6 +356,7 @@ static tree handle_mode_attribute (tree *, tree, tree, int, bool *);
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static tree handle_section_attribute (tree *, tree, tree, int, bool *);
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static tree handle_aligned_attribute (tree *, tree, tree, int, bool *);
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static tree handle_weak_attribute (tree *, tree, tree, int, bool *) ;
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static tree handle_noplt_attribute (tree *, tree, tree, int, bool *) ;
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static tree handle_alias_ifunc_attribute (bool, tree *, tree, tree, bool *);
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static tree handle_ifunc_attribute (tree *, tree, tree, int, bool *);
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static tree handle_alias_attribute (tree *, tree, tree, int, bool *);
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@ -705,6 +706,8 @@ const struct attribute_spec c_common_attribute_table[] =
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handle_aligned_attribute, false },
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{ "weak", 0, 0, true, false, false,
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handle_weak_attribute, false },
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{ "noplt", 0, 0, true, false, false,
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handle_noplt_attribute, false },
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{ "ifunc", 1, 1, true, false, false,
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handle_ifunc_attribute, false },
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{ "alias", 1, 1, true, false, false,
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@ -8184,6 +8187,25 @@ handle_weak_attribute (tree *node, tree name,
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return NULL_TREE;
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}
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/* Handle a "noplt" attribute; arguments as in
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struct attribute_spec.handler. */
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static tree
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handle_noplt_attribute (tree *node, tree name,
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tree ARG_UNUSED (args),
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int ARG_UNUSED (flags),
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bool * ARG_UNUSED (no_add_attrs))
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{
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if (TREE_CODE (*node) != FUNCTION_DECL)
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{
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warning (OPT_Wattributes,
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"%qE attribute is only applicable on functions", name);
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*no_add_attrs = true;
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return NULL_TREE;
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}
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return NULL_TREE;
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}
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/* Handle an "alias" or "ifunc" attribute; arguments as in
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struct attribute_spec.handler, except that IS_ALIAS tells us
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whether this is an alias as opposed to ifunc attribute. */
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@ -221,10 +221,16 @@ prepare_call_address (tree fndecl_or_type, rtx funexp, rtx static_chain_value,
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&& targetm.small_register_classes_for_mode_p (FUNCTION_MODE))
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? force_not_mem (memory_address (FUNCTION_MODE, funexp))
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: memory_address (FUNCTION_MODE, funexp));
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else if (flag_pic && !flag_plt && fndecl_or_type
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else if (flag_pic
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&& fndecl_or_type
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&& TREE_CODE (fndecl_or_type) == FUNCTION_DECL
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&& (!flag_plt
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|| lookup_attribute ("noplt", DECL_ATTRIBUTES (fndecl_or_type)))
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&& !targetm.binds_local_p (fndecl_or_type))
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{
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/* This is done only for PIC code. There is no easy interface to force the
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function address into GOT for non-PIC case. non-PIC case needs to be
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handled specially by the backend. */
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funexp = force_reg (Pmode, funexp);
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}
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else if (! sibcallp)
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@ -25495,13 +25495,19 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1,
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}
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else
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{
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/* Static functions and indirect calls don't need the pic register. */
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/* Static functions and indirect calls don't need the pic register. Also,
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check if PLT was explicitly avoided via no-plt or "noplt" attribute, making
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it an indirect call. */
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if (flag_pic
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&& (!TARGET_64BIT
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|| (ix86_cmodel == CM_LARGE_PIC
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&& DEFAULT_ABI != MS_ABI))
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&& GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF
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&& ! SYMBOL_REF_LOCAL_P (XEXP (fnaddr, 0)))
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&& !SYMBOL_REF_LOCAL_P (XEXP (fnaddr, 0))
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&& flag_plt
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&& (SYMBOL_REF_DECL ((XEXP (fnaddr, 0))) == NULL_TREE
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|| !lookup_attribute ("noplt",
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DECL_ATTRIBUTES (SYMBOL_REF_DECL (XEXP (fnaddr, 0))))))
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{
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use_reg (&use, gen_rtx_REG (Pmode, REAL_PIC_OFFSET_TABLE_REGNUM));
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if (ix86_use_pseudo_pic_reg ())
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@ -25597,6 +25603,31 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1,
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return call;
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}
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/* Return true if the function being called was marked with attribute "noplt"
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or using -fno-plt and we are compiling for non-PIC and x86_64. We need to
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handle the non-PIC case in the backend because there is no easy interface
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for the front-end to force non-PLT calls to use the GOT. This is currently
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used only with 64-bit ELF targets to call the function marked "noplt"
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indirectly. */
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static bool
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ix86_nopic_noplt_attribute_p (rtx call_op)
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{
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if (flag_pic || ix86_cmodel == CM_LARGE
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|| !TARGET_64BIT || TARGET_MACHO || TARGET_SEH || TARGET_PECOFF
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|| SYMBOL_REF_LOCAL_P (call_op))
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return false;
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tree symbol_decl = SYMBOL_REF_DECL (call_op);
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if (!flag_plt
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|| (symbol_decl != NULL_TREE
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&& lookup_attribute ("noplt", DECL_ATTRIBUTES (symbol_decl))))
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return true;
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return false;
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}
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/* Output the assembly for a call instruction. */
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const char *
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@ -25608,7 +25639,9 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op)
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if (SIBLING_CALL_P (insn))
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{
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if (direct_p)
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if (direct_p && ix86_nopic_noplt_attribute_p (call_op))
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xasm = "%!jmp\t*%p0@GOTPCREL(%%rip)";
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else if (direct_p)
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xasm = "%!jmp\t%P0";
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/* SEH epilogue detection requires the indirect branch case
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to include REX.W. */
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@ -25651,7 +25684,9 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op)
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seh_nop_p = true;
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}
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if (direct_p)
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if (direct_p && ix86_nopic_noplt_attribute_p (call_op))
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xasm = "%!call\t*%p0@GOTPCREL(%%rip)";
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else if (direct_p)
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xasm = "%!call\t%P0";
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else
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xasm = "%!call\t%A0";
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@ -2916,6 +2916,35 @@ the standard C library can be guaranteed not to throw an exception
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with the notable exceptions of @code{qsort} and @code{bsearch} that
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take function pointer arguments.
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@item noplt
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@cindex @code{noplt} function attribute
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The @code{noplt} attribute is the counterpart to option @option{-fno-plt} and
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does not use PLT for calls to functions marked with this attribute in position
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independent code.
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@smallexample
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@group
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/* Externally defined function foo. */
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int foo () __attribute__ ((noplt));
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int
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main (/* @r{@dots{}} */)
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@{
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/* @r{@dots{}} */
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foo ();
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/* @r{@dots{}} */
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@}
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@end group
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@end smallexample
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The @code{noplt} attribute on function foo tells the compiler to assume that
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the function foo is externally defined and the call to foo must avoid the PLT
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in position independent code.
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Additionally, a few targets also convert calls to those functions that are
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marked to not use the PLT to use the GOT instead for non-position independent
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code.
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@item optimize
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@cindex @code{optimize} function attribute
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The @code{optimize} attribute is used to specify that a function is to
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@ -23872,6 +23872,14 @@ PLT stubs expect GOT pointer in a specific register, this gives more
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register allocation freedom to the compiler. Lazy binding requires PLT:
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with @option{-fno-plt} all external symbols are resolved at load time.
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Alternatively, function attribute @code{noplt} can be used to avoid PLT
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for calls to specific external functions by marking those functions with
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this attribute.
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Additionally, a few targets also convert calls to those functions that are
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marked to not use the PLT to use the GOT instead for non-position independent
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code.
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@item -fno-jump-tables
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@opindex fno-jump-tables
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Do not use jump tables for switch statements even where it would be
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@ -1,3 +1,10 @@
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2015-06-04 Sriraman Tallam <tmsriram@google.com>
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* testsuite/gcc.target/i386/noplt-1.c: New test.
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* testsuite/gcc.target/i386/noplt-2.c: New test.
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* testsuite/gcc.target/i386/noplt-3.c: New test.
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* testsuite/gcc.target/i386/noplt-4.c: New test.
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2015-06-04 Thomas Koenig <tkoenig@netcologne.de>
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PR fortran/58749
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@ -0,0 +1,13 @@
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/* { dg-do compile { target x86_64-*-linux* } } */
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/* { dg-options "-fno-pic" } */
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__attribute__ ((noplt))
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void foo();
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int main()
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{
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foo();
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return 0;
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}
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/* { dg-final { scan-assembler "call\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */
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@ -0,0 +1,13 @@
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/* { dg-do compile { target x86_64-*-linux* } } */
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/* { dg-options "-O2 -fno-pic" } */
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__attribute__ ((noplt))
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int foo();
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int main()
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{
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return foo();
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}
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/* { dg-final { scan-assembler "jmp\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */
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@ -0,0 +1,12 @@
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/* { dg-do compile { target x86_64-*-linux* } } */
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/* { dg-options "-fno-pic -fno-plt" } */
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void foo();
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int main()
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{
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foo();
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return 0;
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}
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/* { dg-final { scan-assembler "call\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */
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@ -0,0 +1,11 @@
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/* { dg-do compile { target x86_64-*-linux* } } */
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/* { dg-options "-O2 -fno-pic -fno-plt" } */
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int foo();
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int main()
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{
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return foo();
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}
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/* { dg-final { scan-assembler "jmp\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */
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